DEAR MAYO CLINIC: Is it true that adults should be vaccinated against pertussis? I thought that was a childhood disease. Hasn’t it basically been eliminated in the United States?

ANSWER: Now more than ever, it’s important for everyone — including adults — to be vaccinated against pertussis. There is an effective vaccine against pertussis, also known as whooping cough. But the immunity generated by the vaccine weakens over time. When enough people in the population become susceptible to infection, an epidemic can occur. These epidemics are not as severe as was seen in the pre-vaccine era, but they still affect a lot of people. Currently, there are large outbreaks of pertussis in Washington, Minnesota and Wisconsin.

Pertussis is a highly contagious bacterial infection that causes a severe, hacking cough. The coughing spells can be followed by a high-pitched intake of breath that sounds like a “whoop” and gives the disease its name. Coughing spasms can cause extreme fatigue and vomiting and make breathing difficult. In babies, the disease can be very serious because their airways are tiny and they may have trouble breathing in enough oxygen during coughing spells. Severe coughing spells can also generate small hemorrhages in the eyes and brain.

Vaccination is the most important way to prevent pertussis. Infants should be vaccinated at ages 2, 4 and 6 months. The pertussis vaccination is given in combination with tetanus and diphtheria vaccines, which is abbreviated as DTaP for diphtheria, tetanus and acellular pertussis.

Boosters are recommended at 12 to 18 months; 4 to 6 years; and again at age 11. Pertussis booster shots are available for adults, too, and are strongly recommended for those in close contact with infants, particularly during an outbreak. Ask your physician if you can receive Tdap (tetanus-diphtheria-acellular pertussis) vaccine instead of the usual Td (tetanus-diphtheria) booster. The Tdap vaccine can be given anytime, regardless of how recently the person received their last Td booster. Tdap (given to older children and adults) is slightly different from DTaP (given to infants) in that it has a lower amount of diphtheria and pertussis antigens, hence the lowercase “d” and “p.”

Pertussis vaccines are very safe, effective and beneficial. Before the vaccine was available, pertussis was a greatly feared disease that killed thousands of children every year. Now, perhaps 10 to 20 pertussis deaths occur per year in the United States. Almost all of these deaths occur in young infants.

People of all ages still contract the disease. Since the 1980s, pertussis incidence has been increasing in the United States. In a typical year, 5,000 to 10,000 cases are reported, according to the U.S. Centers for Disease Control and Prevention (CDC). But epidemics occur every three to five years. In 2010, more than 27,000 cases were reported in the United States.

We continue to see pertussis for several reasons. One, vaccinations aren’t universal. The CDC estimates that about 85 percent of children between ages 19 and 35 months are fully immunized against pertussis. The rates in adolescents are about 70 percent. In adults, fewer than 10 percent have received Tdap. So the last time most adults were immunized against pertussis was when they were children.

In addition, over time the vaccine’s effectiveness wanes, so we see adolescents and adults with pertussis. These older patients typically have a milder form of the illness because they retain some immunity from early vaccinations. But patients with mild pertussis are still contagious. The disease can be transmitted via germ-laden droplets propelled into the air from a cough or sneeze.

Pertussis is typically diagnosed by inserting a thin swab through the nose to the back of the throat. Collected fluid is then sent for culture or other more rapid tests. Cultures and other tests are not always positive, so some patients will be treated based on symptoms. Regardless of their vaccination history, those with pertussis should be treated with a specific antibiotic. People with pertussis should be kept home from school, day care, or work until they’ve had five days of antibiotics. A doctor may recommend antibiotics for everyone in the household because pertussis is easily transmitted.

Antibiotics work best when given early in the course of the illness. Treatment doesn’t immediately stop the cough; pertussis is also called the 100-day cough because symptoms can linger that long.

Home care includes plenty of rest and fluids. Cough medications aren’t helpful and aren’t recommended. Infants may need to be monitored in a hospital to make sure they can breathe on their own after a coughing spell.

The key is to prevent pertussis from occurring. Make sure that all infants and children — as well as adult family members and caregivers — are fully vaccinated against pertussis. — Thomas Boyce, M.D., and W. Charles Huskins, M.D., Pediatric Infectious Diseases, Mayo Clinic, Rochester, Minn.

Medical Edge from Mayo Clinic is an educational resource and doesn’t replace regular medical care. Email a question to medicaledge@mayo.edu. For more information, visit www.mayoclinic.org.